WikiMechanics

Any hazardous perceptions of heat or cold are called dangerous thermal sensations. We use words like icy, boiling, freezing, scorching, frosty and blistering to describe these sensations. They are not like touching a living person, temperatures are significantly higher or lower. The reference experience for these sensations is touching ice. So to make a binary description of a dangerous thermal sensation, compare it to touching ice. Report the result using one of the following algebraic statements. If the two experiences are not comparable, then say that the sensation is not dangerous and express this by writing $\delta_{T}=0$. If the sensation is like touching ice, then say that it is freezing. Express this as $\delta_{T}=+1$. If the sensation is not like touching ice, then say that it is burning and that $\delta_{T}=-1$. The number $\delta_{T}$ is called the coldness.

Summary

Adjective		Definition
Coldness	$\delta_{T} \equiv \begin{cases} +1 &\sf{\text{if a thermal sensation is freezing }} \\ \; \; 0 &\sf{\text{if a sensation is not thermally dangerous }} \\ -1 &\sf{\text{if a thermal sensation is burning }} \end{cases}$	2-5